Closure with a pressure compensation valve for a liquid container

ABSTRACT

The closure has a bung-type socket (10) of soft elastic material with a flange-like outer bearing portion (12), a circumferential sealing portion (16) sealingly receiving the rim of the hole, and a circumferential snap-action portion (18) engaging the inside of the rim of the hole from behind. In the sealing portion (16) and the snap-action portion (18) of the bung-type socket (10) there is embedded a coaxial reinforcing ring (20) of hard plastic, which is radially rippled over the circumference and thereby is covered by the soft-elastic material in thickness varying over the circumference. The bung-type socket (10) has a central orifice (24), in which a manually adjustable valve element (26) of the pressure-compensating valve occupies a sealing closed position and a pressure-compensating position.

BACKGROUND OF THE INVENTION

The invention relates to a closure with pressure-compensating valve forthe filling hole of a liquid container, with a bung-type socket of softelastic material which fits into the round hole and has a flange-likeouter bearing portion, a circumferential sealing portion sealinglyreceiving the rim of the hole, a circumferential snap-action portionengaging the inside of the rim of the hole from behind, and a centralorifice, and with a valve element which can be manually moved intoposition and. which occupies in the central orifice a sealing closedposition and a pressure-compensating position, in which the interior ofthe container is in communication with the atmosphere.

Such a closure is known from German Patent DE 4219571 C2. It can be usedfor containers in the form of kegs, mini-kegs (party kegs) or cans, fromwhich liquids, especially beverages, are drawn without pressure or underpressure. It is usable in particular for party kegs for beer.

As set forth in the introduction of German Patent DE 3345619 C2, thesnap-action and sealing properties of the bung-type socket of theclosure are subject to considerable and in some cases conflictingrequirements. To meet these, DE 3345619 C2 proposes making the bung-typesocket of a soft part and a hard part, which encloses the soft part inthe manner of a cage and through which the soft part penetrates at theapertures between the bars of the cage. The flange-like outside bearingportion of the soft part is stiffened with a flange on the hard part,and outwardly protruding snap catches are provided on the hard part.

A disadvantage of this bung-type socket is its complex structure, whichnecessitates injection molding of the hard part in a first step, afterwhich the soft part is injection-molded thereonto in a second step.Because of the fact that hard and soft portions alternate over thecircumference of the bung-type socket, a leaktightness problem can occurat the edges therebetween. In addition, deposits can accumulate here,with the potential for undesired bacterial growth.

SUMMARY OF THE INVENTION

The object of the invention is to provide a closure of the type cited inthe introduction with a bung-type socket which is reinforced with hardplastic, but which has a homogeneous soft surface and such simplifiedstructure that fabrication in the two-plastic injection-moldingtechnique is possible.

This object is achieved with such a closure by the fact that there isembedded in the sealing portion and snap-action portion of the bung-typesocket a coaxial reinforcing ring of hard plastic, which is radiallyrippled over the circumference and thereby is covered by thesoft-elastic material in thickness varying over the circumference.

In one preferred embodiment, the snap-action portion and the reinforcingring have a hook-like profile which is identical everywhere over thecircumference.

The bung-type socket of the closure according to the invention ispreferably made by the two-plastic injection-molding technique.

In another preferred embodiment, the valve element in closed positionand pressure-compensating position snaps onto the bung-type socket.

In the central orifice, the valve element can be moved between closedposition and pressure-compensating position by turning and/or by axialdisplacement. The valve element can be positioned purely by turning andalso purely by axial displacement, in which case pressing the valveelement into the bung-type socket for pulling it out of the bung-typesocket can be used equally well for moving the valve element from closedposition to pressure-compensating position and vice versa. Positioningof the valve element by combined turning and axial displacement,especially by quarter-turn adjustment in the manner of a bayonetfastener, is also possible.

In another preferred embodiment the valve element has at least onehandle for turning and/or pulling out. Preferably the handle can be laidflat against the upper side of the bung-type socket. When laid flat itcan be disposed flush in a recess of the bung-type socket, so that itdoes not bear load under storage and transportation conditions. Inanother preferred embodiment the recess has a widened portion, by whichthe handle can be grasped from underneath while laid flat.

In another preferred embodiment, the closure has anoriginality-protecting feature, which reveals whether or not thepressure-compensating valve has already been actuated.

In another preferred embodiment, the valve element is provided with aliftable curved handle, which is fastened to the valve element by meansof ribs, which break away when the handle is lifted for the first time.

The closure known from German Patent DE 4219571 C2 has a bung-typesocket with alternately larger and smaller axial ventilation groovesalong the wall of the central orifice and a valve element withalternately larger and smaller axial ventilation fins along the outsidesurface. The valve element has closed positions, in which matchinggrooves and fins are in engagement, and pressure-compensating positions,in which non-matching grooves and fins are in engagement.

When the liquid container is completely filled, the bung-type socketdips with its lower end into the liquid. Actuation of thepressure-compensating valve then has the consequence that liquid emergesfrom the container. A further disadvantage is that it is difficult todistinguish whether the valve element of the pressure-compensating valveis in one of the plurality of possible closed positions orpressure-compensating positions.

The subject matter of another preferred embodiment of the invention is asatisfactorily hygienic, simply and safely operable closure, which iscapable of achieving pressure compensation when the container iscompletely full.

In this embodiment, the bung-type socket has a lateralpressure-compensating duct, the outside end of which is disposed abovethe liquid level in the completely filled container. The valve elementcan be turned within limits defined by stops from a clearly definedclosed position to a clearly defined pressure-compensating position andback. The valve element in pressure-compensating position opens up aflow path from the inside end of the pressure-compensating duct to theupper side of the bung-type socket, while in closed position it shutsoff the path on the inside, covers it on the outside and seals ittightly on both inside and outside.

The clear definition of a closed position and pressure-compensatingposition and the action of turning the valve element therebetween withinlimits defined by stops make this closure very safe to operate. Thepositions can be clearly marked, and it is apparent at any time whetherthe valve element is in closed position or pressure-compensatingposition. The outside cover and seal of the pressure-compensating flowpath when the valve element is in closed position ensure that noresidual liquid or rinse liquid can enter the closure during the fillingprocess. The closure therefore satisfies the most stringent hygienerequirements.

In one preferred embodiment, the valve element has an external flange,which fits into a recess of the bung-type socket. On the bottom of therecess there is provided a groove extending outward from the centralorifice. The valve element has a surface groove, which inpressure-compensating position brings the inside end of thepressure-compensating duct into communication with the groove on thebottom of the recess.

In another preferred embodiment, the flange of the valve element isnoncircular. In closed position and pressure-compensating position itsnaps radially onto the outside of the bung-type socket with aprojection. In closed position the projection covers the outside end ofthe groove on the bottom of the recess.

In another preferred embodiment, the valve element is notched over thecircumference. The bung-type socket is provided with a cog, whichlocates the notch and becomes stopped at the ends thereof, therebylimiting the adjustment angle of the valve element and defining theclosed position and pressure-compensating position.

In another preferred embodiment, the portion of the valve elementdisposed opposite the inside end of the pressure-compensating duct formsin circumferential direction a ramp, which descends in turning directionfrom closed position to pressure-compensating position. By virtue ofthis ramp, the initial bias exerted by the seal against the inside endof the pressure-compensating duct is gradually relaxed when the valveelement is turned from closed position to pressure-compensatingposition. This opens up the possibility of smooth, gradual pressurecompensation, and in particular careful pressure relief, for examplebefore beer is tapped for the first time.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail hereinafter by referenceto five practical examples illustrated in the drawing, wherein:

FIG. 1 shows a diametral section through a first bung-type socket;

FIG. 2 shows a reinforcing ring of the bung-type socket in axialhorizontal projection;

FIG. 3 shows in side view a valve element seated in the bung-typesocket;

FIG. 4 shows an axial horizontal projection of the valve element seen indirection IV of FIG. 3;

FIG. 5 shows a diametral section through the first bung-type socket withvalve element in closed position indicated by broken lines, the valveelement also being shown separately in side view of the removedcondition with curved handles pivoted upward;

FIG. 6 shows a diametral section through the first bung-type socket withvalve element in pressure-compensating position indicated by brokenlines;

FIG. 7 shows a diametral section through a second bung-type socket withvalve element in closed position indicated by broken lines;

FIG. 8 shows a reinforcing ring of the bung-type socket in axialhorizontal projection;

FIG. 9 shows an axial horizontal projection of the bung-type socket seenin direction IX of FIG. 7;

FIG. 10 shows as a detail the valve element in side view;

FIG. 11 shows a diametral section through the second bung-type socketwith valve element in pressure-compensating position indicated by brokenlines;

FIG. 12 shows a diametral section through a third bung-type socket;

FIG. 13 shows a reinforcing ring of the bung-type socket in axialhorizontal projection;

FIG. 14 shows an axial horizontal projection of the bung-type socketseen in direction XIV of FIG. 12;

FIG. 15 shows the side view of a valve element belonging to the thirdbung-type socket;

FIG. 16 shows a horizontal projection thereof seen in direction XVI ofFIG. 15;

FIG. 17 shows a diametral section through the third bung-type socketwith valve element in closed position indicated by broken lines, thevalve element also being shown separately in removed condition;

FIG. 18 shows a diametral section through the third bung-type socketwith valve element in pressure-compensating position indicated by brokenlines, the valve element again also being shown separately in removedcondition, turned by 90° relative to FIG. 17;

FIG. 19 shows a diametral section through a fourth bung-type socket;

FIG. 20 shows a reinforcing ring of the bung-type socket in axialhorizontal projection;

FIG. 21 shows an axial horizontal projection of the fourth bung-typesocket seen in direction XXI of FIG. 19;

FIG. 22 shows the side view of a valve element belonging to the fourthbung-type socket;

FIG. 23 shows a horizontal projection thereof seen in direction XXIII ofFIG. 22;

FIG. 24 shows a diametral section through the fourth bung-type socketwith valve element in closed position indicated by broken lines, thevalve element also being shown separately in removed condition;

FIG. 25 shows a diametral section through the third bung-type socketwith valve element in pressure-compensating position indicated by brokenlines, the valve element again also being shown separately in removedcondition, turned by 90° relative to FIG. 24;

FIG. 26 shows the side view of the valve element of a fifth closure withpressure-compensating valve;

FIG. 27 shows a horizontal projection from above of the valve elementseen in direction XXVII of FIG. 26;

FIG. 28 shows a horizontal projection from below of the valve elementseen in direction XXVIII of FIG. 26;

FIG. 29 shows the diametral cross-sectional view through a bung-typesocket belonging to the closure;

FIG. 30 shows a reinforcing ring of the bung-type socket in axialhorizontal projection;

FIG. 31 shows a horizontal projection from above of the bung-type socketseen in direction XXXI of FIG. 29; and

FIG. 32 shows in horizontal projection from above an assembly drawing ofbung-type socket and valve element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The closures described hereinafter function to close tightly the fillinghole of a liquid container. Examples of such containers are kegs,mini-kegs (party kegs) or cans, from which liquids, especiallybeverages, can be drawn without pressure or under pressure. It is usablein particular for party kegs for beer.

The filling hole of such containers is a round hole, which is upwardlyopen during the filling process. The closure contains a bung-type socket10 of elastic material, which on the outside is substantiallyrotationally symmetric relative to its central axis and which has anoutwardly protruding flange 12, with which it bears against the outsidewall of the container. Bung-type socket 10 extends with a substantiallyconical tapering portion 14 into the container. The generating line oftapering portion 14 is sigmoidally curved. Between flange 12 andtapering portion 14 the diameter of bung-type socket 10 is recessed toform a sealing portion 16 with the shape of an annular groove, intowhich the rim of the filling hole fits sealingly when bung-type socket10 is forced into place. The section of larger diameter of bung-typesocket 10 forms on the inside in front of sealing portion 16 acircumferential snap-action portion 18 with a hook-like profile which isidentical everywhere over the circumference.

In the region of sealing portion 16 and snap-action portion 18,bung-type socket 10 is stiffened by a reinforcing ring 20 of hardplastic completely embedded therein. For reasons of structuralsimplification, flange 12 of the bung-type socket is not stiffened.

Reinforcing ring 20 has a hook-like profile which is identicaleverywhere over the circumference. It is disposed coaxially withbung-type socket 10 and is rippled radially over the circumference.Thereby reinforcing ring 20 has four radial swellings 22 disposed at 90°intervals, at which swellings the covering of soft plastic material onbung-type socket 10 is thinner than therebetween.

To dispense liquid, the container has a lower dispensing orificeseparate from the filling hole. This can be a bunghole, which is tappedwith a tapping fitting or similar device, or a spigot integrated intothe container.

Vibrations during transportation and/or warming can cause in beer kegsbuild-up of considerable overpressure, with the result that almostexclusively foam is tapped at first. It is recommended that thisoverpressure be carefully relieved before tapping for the first time.For this purpose bung-type socket 10 is equipped with a manuallyoperated pressure-compensating valve.

When liquid is dispensed from the lower dispensing orifice withoutpressure, a partial vacuum is produced above the liquid level in thecontainer. To break this partial vacuum, air can be admitted to thecontainer via the pressure-compensating valve.

Bung-type socket 10 has a central orifice 24, in which valve element 26of the pressure-compensating valve is seated. Valve element 26 isaccessible from the outside to allow valve operation. In central orifice24 of bung-type socket 10 it optionally occupies a sealing closedposition or a pressure-compensating position, in which the interior ofthe container above the liquid level therein is in communication withthe atmosphere.

In the variant shown in FIG. 1 to FIG. 6, bung-type socket 10 has athrough-going axial central orifice 24, the diameter of which isstepped, becoming narrower from outside to inside. On the surface of theorifice portion of larger diameter there are disposed two inwardlyprotruding annular beads 28, 30 at an axial distance from each other.

Valve element 26 has on its outside a flange 32, which fits into arecess 34 on the outside of the flange of bung-type socket 10. Adjoiningthe inside of flange 32 there is disposed a plain cylindrical sealingportion 36 of smaller diameter and thereon a circumferential shoulder 38which projects radially outward. Still further toward the interior,valve element 26 forms a square cross, arms 40 of which are providedwith notches 42 at the same axial height. At its interior end, valveelement 26 has a rotationally symmetric sealing head 44.

On the outside of the flange of valve element 26 there are attached twooppositely disposed curved handles 46, each extending over almost halfthe circumference of valve element 26. In storage and transportationposition, curved handles 46 rest flat in recess 34 of bung-type socket10. To operate the pressure-compensating valve, they are pivoted upwardin order to pull valve element 26 a short distance out of bung-typesocket 10.

As shown in FIG. 5, valve element 26 has in central orifice 24 ofbung-type socket 10 a sealing closed position, in which sealing head 44occupies the interior portion of smaller diameter of central orifice 24.Shoulder 38 of valve element 26 is brought into position between annularbeads 28, 30 of bung-type socket 10. Outer annular bead 28 cooperateswith sealing portion 36 of valve element 26 to form a dust barrier.

As shown in FIG. 6, valve element 26 can be pulled sufficiently far outof bung-type socket 10 that sealing head 44 emerges from the portion ofsmaller diameter of central orifice 24 and inner annular bead 30 snapsinto notches 42 of valve element 26. Sealing portion 36 of valve element26 becomes clear of outer annular bead 28, so that here there isreleased an annular gap and a flow path into the interior of thecontainer between arms 40 of the cross of the valve element.

In the variant shown in FIG. 7 to FIG. 11, through-going central orifice24 of bung-type socket 10 has substantially plain cylindrical shape andis provided with annular beads 28, 30 at its outside and inside endsrespectively.

Valve element 26 has on the outside a round plate 48, the diameter ofwhich corresponds to the inside width of central orifice 24. At theinside of plate 48 there adjoins a first plain cylindrical sealingportion 50 of smaller diameter, in which outer annular bead 28 engages.Further toward the interior, valve element 26 forms a square cross. Atthe interior end, valve element 26 has a second plain cylindricalsealing portion 52 of smaller diameter for inner annular bead 30 and aflange 56 bearing on interior end face 54 of bung-type socket 10.

Valve element 26 is forced into bung-type socket 10 in order to move itfrom closed position to pressure-compensating position. In the latterposition, inner annular bead 30 snaps into notches on arms 40 of thecross of the valve element.

To allow it to be pulled out again, valve element 26 has a centralgripping strap 58 attached to outside plate 48, which strap extendssideways over flange 12 of burg-type socket 10 and in storage andtransportation position rests flat in a recess 34 thereof. When valveelement 26 is forced into bung-type socket 10, gripping strap 58 isautomatically moved to upright position.

In the variant shown in FIGS. 12 to 18, bung-type socket 10 has acentral orifice 24 in the form of a conical blind hole, which taperstoward the interior and ends in a plain cylindrical throat 60 and asubstantially plain cylindrical section 62 of larger diameter. Flange 12of bung-type socket 10 has on the outside a plain cylindrical recess 34and therebehind, toward the interior, an annular bead 28, whichprotrudes inward beyond the conical surface of central orifice 24. Atthe conical surface there extends a radial bore 64, which passestransversely through bung-type socket 10.

Valve element 26 is substantially conical. It has on the interior end ananchoring head 66, which fits into throat 60 and section 62 of largerdiameter of central orifice 24. On the outside, valve element 26 has aflange 32 which fits into recess 34 of bung-type socket 10. To thisthere is adjoined on the inside a circumferential sealing portion 36 ofsmaller diameter, into which annular bead 28 of bung-type socket 10snaps.

Valve element 26 has an off-centered axial bore 68, which extends to theconical surface of bung-type socket 10, where it communicates with theend of radial bore 64 in a particular angular position of valve element26. For pressure compensation, valve element 26 is turned to thisangular position by means of a diametral gripping ridge 70 attached tothe outside of flange 32, and is restored to sealing closed position bybeing turned back or further.

Flange 32 of valve element 26 is noncircular. It has a radiallyprojecting nose 72, which fits into bulges 74 of recess 34 of thebung-type socket. Thereby the sealing closed position and thepressure-compensating position of valve element 26 are marked and fixedby snap-in effect. The positions are disposed at 90° intervals.

The variant shown in FIG. 20 to FIG. 25 is modified as follows comparedwith that just described:

Valve element 26 has on the outside surface a circumferential recess 76extending over 900. Bung-type socket 10 has on the inside surface aridge 78, which projects into circumferential recess 76 and acts as astop to limit the angle through which valve element 26 can be turned.

In front of the end of radial bore 64, valve element 26 has a sealingbead 80 with a circumferential extent of close to 90°. Sealing bead 80shuts off the end of radial bore 64 and uncovers it only inpressure-compensating position.

Off-centered axial bore 68 of valve element 26 extends only to justunder flange 32 thereof, where it communicates with a radial branch duct82 on the upper side of bung-type socket 10. Branch duct 82 is coveredby flange 32, and in pressure-compensating position of valve element 26is brought into communication with a small axial orifice 84 at the rimof flange 32.

In the variant shown in FIG. 26 to FIG. 32, central orifice 24 ofbung-type socket 10 is an inwardly tapering blind hole of basicallyconical shape, which is not completely axially symmetric but has bothconical surface portions 86, 88, 90 and plain cylindrical surfaceportions 92, 94 distributed over circumference and depth. Valve element26, which is of substantially complementary geometry, thereby has awell-defined mounting position in central orifice 24.

Flange 12 of bung-type socket 10 has on the outside a substantiallyplain cylindrical recess 34 of large diameter and therebehind, towardthe interior of the central orifice, an annular bead 28, which protrudesradially inward beyond conical surface 86 of central orifice 24. Theblind hole ends at the inside in a throat 60 defined by toroidal bead 96and a plain cylindrical section 62 of larger diameter.

At surface 92 of the blind hole there extends a pressure-compensatingduct in the form of a radial bore 64, which passes transversely throughbung-type socket 10 at approximately half height. Once bung-type socket10 has been forced into place, radial bore 64 is disposed above theliquid level in the completely filled container.

Valve element 26 has on the outside a flange 32 which fits into recess34 of bung-type socket 10. To this there is adjoined on the inside asealing portion 36 of smaller diameter, into which outer annular bead 28of bung-type socket 10 snaps. Valve element 26 tapers inwardly withconical surface portions 98, 100, 102 and plain cylindrical surfaceportions 104, 106 to a neck 108, and ends in a plain cylindrical head 66of larger diameter. Inner annular bead 30 of bung-type socket 10 snapsinto place against neck 108.

Valve element 26 has on the outside surface a notch 76 extending for 90°in circumferential direction. Bung-type socket 10 has on the insidesurface a cog 78, which projects into notch 76 and acts as a stoplimiting the angle through which valve element 26 can be turned.

The portion of valve element 26 disposed opposite the inside end ofpressure-compensating duct 64 forms in circumferential direction a ramp,which descends in the turning direction from closed position topressure--compensating position.

Valve element 26 has an axial surface groove 110, which extends from theheight of the inside end of pressure-compensating duct 64 to theunderside of flange 32.

On the bottom of recess 34 of the bung-type socket there is provided agroove 82, which is disposed in the same diametral plane 64 as thepressure-compensating duct and which extends from central orifice 24 ofbung-type socket 10 to the outside rim of recess 34.

Flange 32 of valve element 26 is noncircular. It has a radiallyprojecting nose 72, which fits into two bulges 74 of recess 34 of thebung-type socket. Thereby the sealing closed position and thepressure-compensating position of valve element 26 are marked and fixedby snap-in effect. Groove 82 on the bottom of recess 34 of the bung-typesocket ends in bulge 74 corresponding to pressure-compensating position.

In pressure-compensating position, a flow path between the interior ofthe container and the atmosphere is opened up via pressure-compensatingduct 64, surface groove 110 and groove 82 on the bottom of recess 34. Inclosed position, the outside end of groove 82 is covered and tightlyclosed by nose 72 on flange 32 of valve element 26.

From flange 32 of valve element 26, and extending over half thecircumference thereof, there is branched off a curved handle 46, whichcan be lifted by pivoting around a diametral axis. Curved handle 46 isfastened to valve element 26 with ribs 112, which break off when thehandle is lifted for the first time and form clearly visible fracturefaces. Thereby originality protection is achieved.

Curved handle 46 is flush-mounted in bung-type socket 10. Recess 34 hasa widened portion 114, which extends to the rim of bung-type socket 10and in which there is disposed a prolongation 116 of curved handle 46,which prolongation projects outwardly from flange 32 and can be graspedfrom underneath at the rim.

While curved handle 46 is lifted, valve element 26 can be turned fromclosed position to pressure-compensating position and back.

What is claimed is:
 1. A closure with pressure-compensating valve for afilling hole of a liquid container, with a bung-type socket of softelastic material which fits into the filling hole and has a flange-typeouter bearing portion, a circumferential sealing portion sealinglyreceiving the rim of the hole, a circumferential snap-action portionengaging the inside of the rim of the hole from behind, and a centralorifice, and with a valve element which can be manually moved intoposition and which occupies in the central orifice a sealing closedposition and a pressure-compensating position, in which the interior ofthe container is in communication with the atmosphere, characterized inthat there is embedded in the sealing portion (16) and the snap-actionportion (18) of the bung-type socket (10) a coaxial reinforcing ring(20) of hard plastic, which is radially rippled over the circumferenceand thereby is covered by the soft-elastic material in thickness varyingover the circumference.
 2. A closure according to claim 1, characterizedin that the snap-action portion (18) and the reinforcing ring (20) havea hook-shaped profile which is identical everywhere over thecircumference.
 3. A closure according to claim 1, characterized in thatthe bung-type socket (10) is made in two-plastic injection-moldingtechnique.
 4. A closure according to claim 1, characterized in that thevalve element (26) in closed position and pressure-compensating positionsnaps onto the bung-type socket (10).
 5. A closure according to claim 1,characterized in that, in the central orifice (24), the valve element(26) can be moved between closed position and pressure-compensatingposition by turning and/or by axial displacement.
 6. A closure accordingto claim 1, characterized in that the valve element (26) has at leastone handle (46, 58, 70) for turning and/or pulling out.
 7. A closureaccording to claim 6, characterized in that the handle (46, 58) can belaid flat against the outside of the bung-type socket (10).
 8. A closureaccording to claim 7, characterized in that the handle (46, 58) whenlaid flat rests flush in a recess (34) of the bung-type socket (10). 9.A closure according to claim 8, characterized in that the recess (34)has a widened portion (74), which allows the handle (46) while laid flatto be grasped from underneath.
 10. A closure according to claim 1,characterized in that it has an originality-protecting feature, whichreveals whether or not the pressure-compensating valve has already beenactuated.
 11. A closure according to claim 10, characterized in that thevalve element (26) is provided with a liftable curved handle (46), whichis fastened to the valve element (26) by means of ribs (112), whichbreak away when the handle is lifted for the first time.
 12. A closureaccording to claim 1, characterized in that the bung-type socket (10)has a lateral pressure-compensating duct (64), the outside end of whichis disposed above the liquid level in the completely filled container,in that the valve element (26) can be turned within limits defined bystops from a clearly defined closed position to a clearly definedpressure-compensating position and back, and in that the valve element(26) in pressure-compensating position opens up a flow path from theinside end of the pressure-compensating duct (64) to the upper side ofthe bung-type socket (10), while in closed position it shuts off thepath on the inside, covers it on the outside and seals it tightly onboth inside and outside.
 13. A closure according to claim 12,characterized in that the valve element (26) has an external flange(32), which fits into a recess (34) of the bung-type socket (10), inthat on the bottom of the recess (34) there is provided a groove (82)extending outward from the central orifice (24), and in that the valveelement (26) has a surface groove (110), which in pressure-compensatingposition brings the inside end of the pressure-compensating duct (64)into communication with the groove (82) on the bottom of the recess(34).
 14. A closure according to claim 13, characterized in that theflange (32) is noncircular and in closed position andpressure-compensating position it snaps radially onto the outside of thebung-type socket (10) with a projection (72), and in that in closedposition the projection (72) covers the outside end of the groove (82)on the bottom of the recess (34).
 15. A closure according to claim 12,characterized in that the valve element (26) is notched over thecircumference, and in that the bung-type socket (10) is provided with acog (78), which locates the notch (76) and becomes stopped at the endsthereof, thereby limiting the adjustment angle of the valve element (26)and defining the closed position and pressure-compensating position. 16.A closure according to claim 12, characterized in that the portion ofthe valve element (26) disposed opposite the inside end of thepressure-compensating duct (64) forms in circumferential direction aramp, which descends in turning direction from closed position topressure-compensating position.